The present invention relates to a forehead support for a facial mask used to supply breathable gas to a wearer""s airways.
The invention has been developed primarily for use in supporting a nasal mask used in Continuous Positive Airway Pressure (CPAP) treatment of, for example, Obstructive Sleep Apnea (OSA) and other ventilatory assistance treatments such as Non-Invasive Positive Pressure Ventilation (NIPPV) and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to these particular uses and is also suitable for use with, for example, full-face (ie. nose and mouth) masks.
CPAP treatment is a common ameliorative treatment for breathing disorders including OSA. CPAP treatment, as described in U.S. Pat. No. 4,944,310, provides pressurised air or other breathable gas to the entrance of a patient""s airways at a pressure elevated above atmospheric pressure, typically in the range 4-20 cm H2O.
It is also known for the level of treatment pressure to vary during a period of treatment in accordance with patient need, that form of CPAP being known as automatically adjusting nasal CPAP treatment, as described in U.S. Pat. No. 5,245,995.
NIPPV is another form of treatment for breathing disorders which can involve a relatively higher pressure of gas being provided in the patient mask during the inspiratory phase of respiration and a relatively lower pressure or atmospheric pressure being provided in the patient mask during the expiratory phase of respiration;
In other NIPPV modes the pressure can be made to vary in a complex manner throughout the respiratory cycle. For example, the pressure at the mask during inspiration or expiration can be varied through the period of treatment, as disclosed in the applicant""s international PCT patent application No. PCT/AU97/00631.
Typically, the ventilatory assistance for CPAP or NIPPV treatment is delivered to the patient by way of a nasal mask. Alternatively, a mouth mask or full face mask or nasal prongs can be used. In this specification any reference to a mask is to be understood as incorporating a reference to a nasal mask, mouth mask, full face mask or nasal prongs, unless otherwise specifically indicated.
In this specification any reference to CPAP treatment is to be understood as embracing all of the above described forms of ventilatory treatment or assistance.
A CPAP apparatus broadly comprises a flow generator constituted by a continuous source of air or other breathable gas such as a hospital piped supply or a blower. In the latter case, an electric motor drives the blower and is typically controlled by a servo-controller under the control of a microcontroller unit. In either case, the gas supply is connected to a conduit or tube which in turn is connected to a patient nasal or full-face mask which incorporates, or has in close proximity, an exhaust to atmosphere for venting exhaled gases. Examples of prior art nasal masks are shown in U.S. Pat. Nos. 4,782,832 and 5,243,971.
The supply conduit delivers gas into a chamber formed by walls of the mask. The mask includes a cushion positioned against the wearer""s face and is normally secured to the wearer""s head by straps. The straps are adjusted to pull the mask against the face to achieve a gas tight seal between the cushion and the wearer""s face.
A problem that arises with existing masks is that with the use of straps, the mask is compressed against the wearer""s face and may push unduly hard on the wearer""s nose. Additionally, the mask may move around the wearer""s face. Thus, there has been hitherto provided a forehead support, which provides a support mechanism between the mask and the forehead. This forehead support prevents both the mask from pushing too strongly against the wearer""s nose and/or facial region as well as minimising movement of the mask with the addition of a contact point between the mask and the wearer""s head thereby reducing uncomfortable pressure points. Additionally, the forehead support can be arranged to prevent the gas supply conduit from contacting the wearer""s forehead or face.
Forehead supports with a single cushion and a single contact point on the forehead are known.
The applicant""s U.S. patent application Ser. No. 09/008,708 relates to a substantially rigid one-piece forehead support having a pair of forehead cushions mounted at each outer end of the support. This forehead support is connected to the top of a facial mask and includes an adjustment mechanism to allow the spacing between the top of the facial mask and the forehead support to be altered between predetermined positions to alter the angle of the mask relative to the wearer""s head to suit the wearer""s facial topography.
The applicant""s Australian provisional patent application No. PP9499 relates to a forehead support having a pair of pivotable arms that each have a forehead cushion mounted at their distal end. This forehead support is connected to the top of a mask and includes an adjustable mechanism to allow the angle between the arms to be altered between predetermined positions to alter the angle of the mask relative to the wearer""s head to suit the wearer""s facial topography.
It is an object of the present invention to provide an alternate form of forehead support.
Accordingly, in a first aspect, the present invention provides a forehead support adapted to be secured to a respiratory mask, said forehead support including a joining member for securing to the mask and a cushion frame pivotally mounted to the joining member, wherein: the cushion frame is adapted to locate one or more forehead cushions; the cushion frame is adapted to pivot relative to the joining member; and the cushion frame is selectively lockable at two or more predetermined angular positions relative to the joining member.
In a second aspect, the present invention provides a respiratory mask assembly comprising a respiratory mask and a forehead support adapted to be secured to the mask, said forehead support including a joining member for securing to the mask and a cushion frame pivotally mounted to the joining member, wherein: the cushion frame is adapted to locate one or more forehead cushions; the cushion frame is adapted to pivot relative to the joining member; and the cushion frame is selectively lockable at two or more predetermined angular positions relative to the joining member.
The cushion frame is preferably T-shaped and includes a forehead cushion at each end of the upper portion of the T.
Preferably, one of the cushion frame or joining member includes a tongue adapted to be received in one of at least two grooves provided on the other of the cushion frame or joining member so as to lock the cushion frame and joining member at one of the two or more predetermined angular positions.
More preferably, a pair of the tongues are provided on the cushion frame and at least two pairs of grooves are provided on the joining member.
The tongue(s) is/are preferably provided on a semi-rigid member which is adapted to permit the tongue(s) to be moved out of engagement with the grooves by manual manipulation of the member. The tongue(s) is/are preferably connected to a button adapted to protrude from the cushion frame to facilitate manual manipulation of the member.
The cushion frame preferably includes means to connect a head strap thereto.
The mask preferably also include means to connect a head strap thereto.
The joining member can be produced from, for example, polypropylene or polycarbonate.
The mask can include a mask shell and a mask cushion. The mask shell can be produced from, for example, polypropylene or polycarbonate.
The cushion frame can be produced from, for example, polypropylene or polycarbonate.